Distributed power control for uplink virtual multiple-input multiple-output cellular system

The authors study the distributed power control scheme for uplink virtual multiple-input multiple-output (V-MIMO) cellular system, where multi-user equipments (UEs) with single antenna share the same time and frequency resource block. Under the target signal-to-interference-plus-noise ratio and the maximum transmit power constraints, each UE??s power is optimised to minimise the total transmit power through iterative and fully distributed manner. Since the interference of the uplink V-MIMO cellular system not only depends on the UEs transmit power but also on the receiver structure, the convergence properties of the V-MIMO power control scheme rely on specific receiver structure. The authors demonstrate that the well-known standard power control (SPC) for the single-input single-output cellular system also converges to a unique fixed optimal point for the V-MIMO cellular system with zero-forcing and minimum mean square error receiver when the system is feasible. When the system is infeasible, SPC deteriorates. Then the authors present a distributed power control algorithm with gradual soft removal. The algorithm considers different interference tolerance of UEs and removes non-supported UEs with different priorities in order to reduce the outage ratio. The authors prove that their algorithm converges to a unique fixed point. The significant advantage of convergence, outage ratio and energy consummation are also proven by simulations.